Definition from macmillandictionary.com
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Boys usually express their aggression by hitting each other.
So far they had shown no aggression towards him.
We shall unite to defend ourselves against aggression.
The statement condemned the country’s brutal aggression against its neighbour.
an act of unprovoked aggression (=there was no reason for it)
Aggression against the supporters of rival teams is on the increase.
Many of them had been victims of physical aggression.